It may be desirable to track a specific product or item through a manufacturing process. For example, it can be useful to know the position of each product or item in the manufacturing process.
A unique identifier or “ID” is typically assigned to the specific item or a pallet/moving element associated with the item. Based on this unique ID, a manufacturing system can track process data, performance data, product genealogy and the like. Manufacturing systems can also report status, make routing decisions, select assembly options and the like. Examples of existing ID tracking systems in manufacturing include stationary radio frequency (RF) read/write heads with RF tags mounted on the items being tracked, barcode scanners with barcode labels fastened to the items being tracked, and vision cameras reading a unique identification code on the item with optical character recognition (OCR).
There are certain limitations with conventional conveyor ID tracking systems. Firstly, conventional ID readers do not generally provide the location of the item along with the ID that is read. Secondly, in certain conventional ID tracking systems, the ID is only available at stationary readers and not at all positions/times along the path an item is travelling. Thirdly, conventional ID readers can cause delays in a system because the item may have to slow down or stop in front of the reader when the ID is being read. Fourthly, in conventional ID systems, there may need to be physical access to a tag or the like for a reader to be able to read it. Also, the readers will generally occupy physical space for mounting on the system.
Further, conventional systems may be prone to faults. If readers are bumped or shifted, it could lead to failures due to misalignment or excessive gaps. Readers based on optics may be prone to faults due to dirt or an inability to read poor labels. Tags that rely on battery power may be prone to failure when batteries run low. Provisions may need to be made on systems to handle invalid reads. In certain conventional ID tracking systems, added hardware may be required to be incorporated into the system.
There are also certain limitations to conventional position feedback systems. For example, to control and move a pallet on a linear motor based conveyor, the position of each pallet is provided to a controller that precisely controls the pallet movement. This position feedback may be of a high resolution and a high speed. An example of an existing position feedback system used in manufacturing is magnetic readers that read magnetic fields of magnets placed on the pallet or carrier in the form of a magnetic strip or the like.
Conventional position feedback systems may be limited by only providing position of pallets or carriers so their movements can be controlled. Conventional systems may control multiple pallets, using the real time position feedback, but added hardware may be required to track the specific pallet or fixture number that is generally needed for ID tracking.
In the case of a standalone identification reader, it is advantageous to know the precise position of the item along with the unique identifier. Operations or tasks can better be performed when the precise location of the item is known. Take the example of a robot performing an assembly operation on a product in a manufacturing cell. With a unique identification tracking code, the system can determine what operations need to be performed by the robot on the product. If the location of the product is included along with its identification tracking code, the robot would know precisely where the product is located to start working on the product.
In the case of a linear motor conveyor, the location of all pallets is typically known but it is advantageous to also have a unique identifier for each pallet along with the position feedback.
As such, there is a need for improved tracking systems and methods in conveyor systems.